Implantable medical devices have become increasingly more common over the last 50 years and have found applications in nearly every branch of medicine. Examples include joint replacements, vascular grafts, heart valves, ocular lenses, pacemakers, vascular stents, urethral stents, and many others. However, regardless of the application, implantable medical devices must be biocompatible, that is, they must be fabricated from materials that will not elicit an adverse biological response such as, but not limited to, inflammation, thrombogenesis or necrosis. Thus, early medical devices were generally fabricated from inert materials such as precious metals and ceramics. More recently, stainless steel and other metal alloys have replaced precious metals and polymers are being substituted for ceramics.
Polytetrafluoroetheylene (PTFE) is a polymer comprised of carbon chains saturated with fluorine. The use of PTFE in medical applications began in the construction of artificial heart valves. Expanded PTFE is porous, biostable, and implantable medical devices made from it do not degrade within the body.
Expanded polytetrafluoroethylene materials are now widely used in a variety of medical devices; for example, vascular grafts, ablation catheters, etc.
Expanded polytetrafluoroethylene offers many advantageous physical properties relating to medical devices. Along with a low coefficient of friction, ePTFE is biocompatible, chemically resistant, linearly strong, UV resistant, waterproof, flexible, etc. However, ePTFE is extremely hydrophobic and not easily wettable. Medical devices made of ePTFE are non-wetting when introduced into an aqueous environment, limiting their use in certain applications.
Therefore, methods to decrease hydrophobicity, and therefore improve wettability, of ePTFE medical devices are needed to optimize these devices.